This directory contains sample parameter files for the 20 convex
shapes studied in the paper "Sensitivity of Polarization to Grain
Shape: I. Convex Shapes" (Draine 2023, submitted).

For each shape, 3 ddscat.par files are provided, differing in the
number N of dipoles that will be used for the discrete dipole
approximation calculations.  The ddscat.par files collected here have
been given names like

ddscat.par_spheroid_5_7_7_N1
ddscat.par_spheroid_5_7_7_N2
ddscat.par_spheroid_5_7_7_N3

corresponding to the values of N_1, N_2, N_3 in Table 3 of Draine
(2023, submitted).

The desired file should be renamed to just ddscat.par for use in
calculations with DDSCAT 7.3.3

Each ddscat.par file is for one value of the effective radius a_eff =
0.20um.  To do calculations for other values of a_eff (e.g., 0.15um),
simply edit line 31 of the ddscat.par file and change

0.20 0.20  1 'LIN' = aeff (first,last,how many,how=LIN,INV,LOG)

to, e.g.,

0.15 0.15  1 'LIN' = aeff (first,last,how many,how=LIN,INV,LOG)

Also provided here are files for the two astrodust dielectric
functions fron Draine & Hensley (2023) that were used for the
calculations;

astrodust_DH21c_P0.20_0.00_0.500   (used for the "elongated" shapes)
astrodust_DH21c_P0.20_0.00_1.400   (used for the "flattened" shapes)

For more information about ddscat.par files, and the DDSCAT program in
general, please consult the DDSCAT 7.3.3 user guide, available at
http://www.ddscat.org.

References:

Draine, B.T., & Hensley, B.S. 2021, ApJ 909:94
